统一字体资源释放逻辑，封装至辅助方法

将各 View 类中字体相关资源的释放操作统一封装到 LinuxRuntimeFontHelper.ReleaseRuntimeFont 方法中，减少重复代码，提升可维护性。新增多种 ReleaseRuntimeFont 重载，支持不同资源组合的释放需求，并自动清理相关字段和诊断信息。

Author: maikebing

src/LVGLSharp.Runtime.Linux/DrmView.cs

@@ -154,11 +154,13 @@ protected override void OnCloseCore()
             _display = null;
         }
 
-        _fontManager?.Dispose();
-        _fontManager = null;
+        LinuxRuntimeFontHelper.ReleaseRuntimeFontDiagnostics(
+            ref _fallbackFont,
+            ref _fontManager,
+            ref _fontDiagnosticSummary,
+            ref _fontGlyphDiagnosticSummary,
+            ref _defaultFontStyle);
         _resolvedDevicePath = null;
-        _fontDiagnosticSummary = null;
-        _fontGlyphDiagnosticSummary = null;
         _root = null;
         _initialized = false;
     }

src/LVGLSharp.Runtime.Linux/FrameBufferView.cs

@@ -128,8 +128,10 @@ protected override void OnCloseCore()
                 g_display = null;
             }
 
-            _fontManager?.Dispose();
-            _fontManager = null;
+            LinuxRuntimeFontHelper.ReleaseRuntimeFont(
+                ref _fallbackFont,
+                ref _fontManager,
+                ref _defaultFontStyle);
             RootObject = null;
             KeyInputGroupObject = null;
             SendTextAreaFocusCallbackCore = null;

src/LVGLSharp.Runtime.Linux/LinuxRuntimeFontHelper.cs

@@ -140,4 +140,54 @@ internal static LinuxRuntimeFontInitialization InitializeRuntimeFont(
             out _,
             out defaultFontStyle);
     }
+
+    internal static void ReleaseRuntimeFont(
+        ref lv_font_t* fallbackFont,
+        ref SixLaborsFontManager? fontManager,
+        ref lv_style_t* defaultFontStyle)
+    {
+        LvglRuntimeFontRegistry.ClearActiveTextFont();
+        fontManager?.Dispose();
+        fontManager = null;
+        fallbackFont = null;
+        defaultFontStyle = null;
+    }
+
+    internal static void ReleaseRuntimeFontDiagnostics(
+        ref lv_font_t* fallbackFont,
+        ref SixLaborsFontManager? fontManager,
+        ref string? fontDiagnosticSummary,
+        ref string? glyphDiagnosticSummary,
+        ref lv_style_t* defaultFontStyle)
+    {
+        ReleaseRuntimeFont(ref fallbackFont, ref fontManager, ref defaultFontStyle);
+        fontDiagnosticSummary = null;
+        glyphDiagnosticSummary = null;
+    }
+
+    internal static void ReleaseRuntimeFontPathAndDiagnostic(
+        ref lv_font_t* fallbackFont,
+        ref SixLaborsFontManager? fontManager,
+        ref string? resolvedSystemFontPath,
+        ref string? fontDiagnosticSummary,
+        ref lv_style_t* defaultFontStyle)
+    {
+        ReleaseRuntimeFont(ref fallbackFont, ref fontManager, ref defaultFontStyle);
+        resolvedSystemFontPath = null;
+        fontDiagnosticSummary = null;
+    }
+
+    internal static void ReleaseRuntimeFontFull(
+        ref lv_font_t* fallbackFont,
+        ref SixLaborsFontManager? fontManager,
+        ref string? resolvedSystemFontPath,
+        ref string? fontDiagnosticSummary,
+        ref string? glyphDiagnosticSummary,
+        ref lv_style_t* defaultFontStyle)
+    {
+        ReleaseRuntimeFont(ref fallbackFont, ref fontManager, ref defaultFontStyle);
+        resolvedSystemFontPath = null;
+        fontDiagnosticSummary = null;
+        glyphDiagnosticSummary = null;
+    }
 }

src/LVGLSharp.Runtime.Linux/SdlView.cs

@@ -172,11 +172,13 @@ protected override void OnCloseCore()
 
         _bufferPresenter.Dispose();
 
-        _fontManager?.Dispose();
-        _fontManager = null;
-        _resolvedSystemFontPath = null;
-        _fontDiagnosticSummary = null;
-        _fontGlyphDiagnosticSummary = null;
+        LinuxRuntimeFontHelper.ReleaseRuntimeFontFull(
+            ref _fallbackFont,
+            ref _fontManager,
+            ref _resolvedSystemFontPath,
+            ref _fontDiagnosticSummary,
+            ref _fontGlyphDiagnosticSummary,
+            ref _defaultFontStyle);
 
         _root = null;
         _keyInputGroup = null;

src/LVGLSharp.Runtime.Linux/WaylandView.cs

@@ -186,10 +186,12 @@ protected override void OnCloseCore()
             _lvDisplay = null;
         }
 
-        _fontManager?.Dispose();
-        _fontManager = null;
-        _resolvedSystemFontPath = null;
-        _fontDiagnosticSummary = null;
+        LinuxRuntimeFontHelper.ReleaseRuntimeFontPathAndDiagnostic(
+            ref _fallbackFont,
+            ref _fontManager,
+            ref _resolvedSystemFontPath,
+            ref _fontDiagnosticSummary,
+            ref _defaultFontStyle);
 
         _root = null;
         _bufferPresenter.Dispose();

src/LVGLSharp.Runtime.Linux/X11View.cs

@@ -530,12 +530,13 @@ protected override void OnCloseCore()
             _display = IntPtr.Zero;
         }
 
-        LvglRuntimeFontRegistry.ClearActiveTextFont();
-        _fontManager?.Dispose();
-        _fontManager = null;
-        _resolvedSystemFontPath = null;
-        _fontDiagnosticSummary = null;
-        _fontGlyphDiagnosticSummary = null;
+        LinuxRuntimeFontHelper.ReleaseRuntimeFontFull(
+            ref _fallbackFont,
+            ref _fontManager,
+            ref _resolvedSystemFontPath,
+            ref _fontDiagnosticSummary,
+            ref _fontGlyphDiagnosticSummary,
+            ref _defaultFontStyle);
 
         RootObject = null;
         SendTextAreaFocusCallbackCore = null;